1. Field of the Invention
The present invention relates to a technique for managing data files using cloud storages.
2. Background Art
In recent years, it has become discussed to utilize in business public cloud storage services which have been provided for consumers. The file sharing function provided by public cloud storage services is one of advantages in using cloud storages. However, a lot of users are anxious in terms of security when using public cloud storages in business. Thus public cloud storages are generally used for personal use only so far. Therefore, as one of security measures, a scheme has been developed in which files stored in cloud storages are encrypted before operation. In association with this scheme, software products that implement encrypting files stored in cloud storages are available in the market. However, only few products achieve both the file sharing function of public cloud storage services and the encryption.
JP Patent Publication (Kokai) No. 2007-11511 A describes, in a case where a plurality of users shares encrypted files without using cloud storages, a system in which the encrypted files are stored in a removable medium and the encrypted files can be decrypted only on computers that are used by user groups permitted in advance.